HTTP response status codes are crucial in web development, providing valuable insights into the outcome of a client’s request.
In our previous blog posts, we explored Informational Responses (100 – 199), Successful Responses (200 – 299), and Redirection Responses (300 – 399), learning how they establish communication, indicate success, and handle redirects.
Now, let’s dive into the fourth class of HTTP response status codes – Client Error Responses (400 – 499). These codes signify that the client’s request contains errors or cannot be fulfilled. Join us as we explore each of these client error responses in detail.
Table: HTTP Response Status Codes – Client Error Responses
| Status Code | Name | Description | Example |
|---|---|---|---|
| 400 | Bad Request | The server cannot understand the request due to bad syntax or other client-side errors. | HTTP/1.1 400 Bad Request |
| 401 | Unauthorized | The request requires user authentication. The client must provide valid credentials. | HTTP/1.1 401 Unauthorized |
| 402 | Payment Required | Reserved for future use. | HTTP/1.1 402 Payment Required |
| 403 | Forbidden | The server understands the request, but refuses to authorize it. The client should not repeat the request without modifications. | HTTP/1.1 403 Forbidden |
| 404 | Not Found | The requested resource could not be found on the server. It may have been moved or deleted. | HTTP/1.1 404 Not Found |
| 405 | Method Not Allowed | The request method (GET, POST, PUT, DELETE, etc.) is not allowed for the requested resource. | HTTP/1.1 405 Method Not Allowed |
| 406 | Not Acceptable | The requested resource cannot produce a response that is acceptable according to the headers sent in the request. | HTTP/1.1 406 Not Acceptable |
| 407 | Proxy Authentication Required | The client must first authenticate itself with the proxy before making the request to the server. | HTTP/1.1 407 Proxy Authentication Required |
| 408 | Request Timeout | The client took too long to complete the request. | HTTP/1.1 408 Request Timeout |
| 409 | Conflict | The request could not be completed due to a conflict with the current state of the target resource. | HTTP/1.1 409 Conflict |
| 410 | Gone | The requested resource is no longer available at the server and has been permanently removed. | HTTP/1.1 410 Gone |
| 411 | Length Required | The server requires a valid Content-Length header to be included in the request. | HTTP/1.1 411 Length Required |
| 412 | Precondition Failed | The server does not meet one of the preconditions specified by the client in the request headers. | HTTP/1.1 412 Precondition Failed |
| 413 | Payload Too Large | The server refuses to process the request because the request payload is too large. | HTTP/1.1 413 Payload Too Large |
| 414 | URI Too Long | The server refuses to process the request because the URI (Uniform Resource Identifier) provided is too long. | HTTP/1.1 414 URI Too Long |
| 415 | Unsupported Media Type | The server refuses to process the request because the media type of the request data is not supported. | HTTP/1.1 415 Unsupported Media Type |
| 416 | Range Not Satisfiable | The server cannot satisfy the request range specified in the Range header. | HTTP/1.1 416 Range Not Satisfiable |
| 417 | Expectation Failed | The server cannot meet the requirements of the Expect request-header field. | HTTP/1.1 417 Expectation Failed |
| 418 | I’m a teapot | A fun and humorous status code, not to be taken seriously. This code indicates that the server is a teapot, not designed to brew coffee. | HTTP/1.1 418 I’m a teapot |
| 421 | Misdirected Request | The request was directed at a server that is not able to produce a response. | HTTP/1.1 421 Misdirected Request |
| 422 | Unprocessable Entity | The server understands the request, but the request data is semantically incorrect or unable to be processed. | HTTP/1.1 422 Unprocessable Entity |
| 423 | Locked | The requested resource is locked and cannot be accessed. | HTTP/1.1 423 Locked |
| 424 | Failed Dependency | The request failed due to a failure of a previous request. | HTTP/1.1 424 Failed Dependency |
| 425 | Too Early | The server refuses to process the request because it is too early in its processing flow. | HTTP/1.1 425 Too Early |
| 426 | Upgrade Required | The server refuses to perform the request using the current protocol but may be willing to do so if the client upgrades to a different protocol. | HTTP/1.1 426 Upgrade Required |
| 428 | Precondition Required | The server requires the request to be conditional. | HTTP/1.1 428 Precondition Required |
| 429 | Too Many Requests | The user has sent too many requests in a given amount of time. | HTTP/1.1 429 Too Many Requests |
| 431 | Request Header Fields Too Large | The server refuses to process the request because the request headers are too large. | HTTP/1.1 431 Request Header Fields Too Large |
| 451 | Unavailable For Legal Reasons | The server refuses to provide the requested resource due to legal reasons. | HTTP/1.1 451 Unavailable For Legal Reasons |
Client error responses (status codes 400 – 499) indicate that the client’s request contains errors or is not valid for some reason. These codes are essential for identifying and diagnosing issues with client-side requests. When handling these responses, developers should provide clear error messages and guide users towards resolving the issues.
Next, we’ll explore Server Error Responses (500 – 599), which indicate that the server failed to fulfill a valid request. Happy coding!
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